TW202100340A - Light diffusion film, light diffusion film production method, optical member, display panel for image display device, and image display device - Google Patents

Abstract

Provided is a light diffusion film which is capable of offering favorable light diffusion properties and favorable light transmittance. This light diffusion film has a light diffusion layer (B) laminated at least on one side of a transparent substrate (A), and is characterized in that protrusions and recesses are formed on the outermost surface in the light diffusion film on the light diffusion layer (B) side, and the profile of the protrusions and recesses satisfies numerical formulas (1) and (2). Numerical formula (1): 0.110 ≤ Sm. Numerical formula (2): Rsk ≤ 0.200. In numerical formula (1), Sm represents a mean distance (mm) between protrusions and recesses in the protrusion-recess profile as measured in accordance with JIS B0601 (1994). In numerical formula (2), Rsk represents the skewness of the protrusion-recess profile as measured in accordance with JIS B0601 (1994).

Description

Light diffusion film, manufacturing method of light diffusion film, optical member, display panel for image display device, and image display device

The present invention relates to a light diffusion film, a manufacturing method of the light diffusion film, an optical member, a display panel for an image display device, and an image display device.

In an image display device using a backlight, in order to make the amount of light of the entire screen uniform and reduce display unevenness, a light diffusion film is used (Patent Document 1).

Prior art literature Patent literature Patent Document 1: Japanese Patent Application Laid-Open No. 10-096922

Problems to be solved by the invention Once the light-diffusion film improves the light-diffusion property, there is a problem that the light transmittance tends to decrease.

In view of this, the object of the present invention is to provide a light diffusing film, a method of manufacturing a light diffusing film, an optical member, a display panel for an image display device, and an image display device that can balance light diffusibility and light transmittance.

Means to solve the problem To achieve the foregoing objective, the light diffusion film of the present invention, The light diffusion layer (B) is laminated on at least one side of the transparent substrate (A), and is characterized by: Concavities and convexities are formed on the outermost surface of the light diffusion layer (B) side of the light diffusion film, and The aforementioned concavo-convex shape satisfies the following formulas (1) and (2). 0.110≦Sm　　　　　　　　　　　　　　(1) Rsk≦0.200　　　　　　　　　　　　　　(2) In the foregoing mathematical formula (1), Sm is the average distance between the bumps (mm) of the foregoing bumps measured in accordance with JIS B0601 (1994 edition), In the aforementioned formula (2), Rsk is the skewness of the aforementioned uneven shape measured in accordance with JIS B0601 (1994 edition).

The manufacturing method of the light diffusion film of the present invention, It is a method of manufacturing the aforementioned light diffusion film of the present invention, and the manufacturing method is characterized by including the following steps: The light diffusion layer (B) forming step is to form the light diffusion layer (B) on the transparent substrate (A); and The unevenness forming step is to form the unevenness on the outermost surface of the light diffusion layer (B) side of the light diffusion film in a manner that satisfies the foregoing mathematical formulas (1) and (2); The light diffusion layer (B) forming step includes: a coating step of applying a coating liquid on the transparent substrate (A); and a coating film forming step of drying the applied coating liquid to form a coating Membrane; and The aforementioned coating liquid contains resin and solvent.

The optical member of the present invention is an optical member including the light diffusion film of the present invention.

The display panel for an image display device of the present invention is a display panel for an image display device including the light diffusing film of the present invention used on the visible back side of the display panel for an image display device.

The image display device of the present invention is an image display device including the light diffusion film of the present invention, the optical member of the present invention, or the display panel for an image display device of the present invention.

Invention effect According to the present invention, it is possible to provide a light-diffusing film, a method of manufacturing a light-diffusing film, an optical member, a display panel for an image display device, and an image display device capable of both light diffusibility and light transmittance.

The form used to implement the invention Next, an example will be given to further illustrate the present invention in detail. However, the present invention is not limited at all by the following description.

For the light diffusion film of the present invention, for example, the visual transmittance loss rate at a wavelength of 380 to 780 nm can also be below 3.0%.

The light-diffusion film of the present invention may be further laminated with another layer on the surface of the light-diffusion layer (B) opposite to the transparent substrate (A), for example.

The light diffusion film of the present invention can be, for example, the following light diffusion film: A light-diffusing film, which is laminated with a light-diffusing layer (B) and other layers on at least one side of a transparent substrate (A), and is characterized by: Concavities and convexities are formed on the outermost surface of the aforementioned other layers, and The aforementioned concavo-convex shape satisfies the following formulas (1) and (2). 0.110≦Sm　　　　　　　　　　　　　　　(1) Rsk≦0.200　　　　　　　　　　　　　　(2) In the foregoing mathematical formula (1), Sm is the average distance between the bumps (mm) of the foregoing bumps measured in accordance with JIS B0601 (1994 edition), In the aforementioned formula (2), Rsk is the skewness of the aforementioned uneven shape measured in accordance with JIS B0601 (1994 edition).

In the light-diffusing film of the present invention, for example, the aforementioned transparent substrate (A) may also contain acrylic resin.

In the light diffusion film of the present invention, for example, the transparent substrate (A) may be an acrylic film.

In the light diffusion film of the present invention, for example, the aforementioned light diffusion layer (B) may also contain a binder resin and a filler. Moreover, for example, the aforementioned filler may be particles. In addition, for example, the difference in refractive index between the particles and the binder resin may be 0.200 or less.

The light diffusion film of the present invention may have an intermediate layer between the transparent substrate (A) and the light diffusion layer (B), and the intermediate layer includes a resin derived from the transparent substrate (A) and a resin derived from the transparent substrate (A). Resin of light diffusion layer (B).

The light-diffusion film of the present invention may be, for example, a light-diffusion film used on the back side of a display panel for an image display device.

In the method of manufacturing the light diffusion film of the present invention, for example, the light diffusion layer (B) forming step may further include a curing step of curing the coating film.

In the manufacturing method of the light-diffusion film of this invention, the said solvent may contain toluene and cyclopentanone.

In the method of manufacturing the light-diffusing film of the present invention, for example, the light-diffusing film is a light-diffusing film including the other layer, and the uneven forming step may also include forming the other layer on the light-diffusing layer (B) Other layer formation steps.

The image display device of the present invention may be, for example, an image display device including the display panel for the image display device of the present invention and the backlight for the image display device.

[1. Light diffusion film] The light diffusion film of the present invention is a light diffusion film having a light diffusion layer (B) laminated on at least one side of a transparent substrate (A) as described above, and is characterized in that the light diffusion in the light diffusion film Concavities and convexities are formed on the outermost surface of the layer (B) side, and the aforementioned concavity and convexity shapes satisfy the following formulas (1) and (2). 0.110≦Sm　　　　　　　　　　　　　　　(1) Rsk≦0.200　　　　　　　　　　　　　　(2) In the foregoing mathematical formula (1), Sm is the average distance between the bumps (mm) of the foregoing bumps measured in accordance with JIS B0601 (1994 edition), In the aforementioned formula (2), Rsk is the skewness of the aforementioned uneven shape measured in accordance with JIS B0601 (1994 edition).

The light diffusion film of the present invention has a large Sm and a small Rsk. That is, in the light-diffusion film of the present invention, the uneven shape of the outermost surface on the light-diffusion layer (B) side is gentle. Thereby, the light diffusion film of the present invention can have both high light diffusivity and high light transmittance.

For a general light-diffusing film, for example, for light diffusibility, the peaks and peaks in the uneven shape of the surface are short, and the valleys have more components relative to the center line of the surface height, resulting in large unevenness. As a result, the loss of light becomes larger and the light transmittance decreases. In this regard, the inventors found that by setting the aforementioned Sm within the range of the aforementioned mathematical formula (1) and setting the aforementioned Rsk within the aforementioned mathematical formula (2), both light diffusibility and light transmittance can be achieved. In the light-diffusing film of the present invention, the aforementioned Sm is as large as 0.110 or more, that is, the interval between the peak portion and the peak portion in the uneven shape of the surface is long. In addition, the aforementioned Rsk is as small as 0.200 or less, which means that the components of the peaks and valleys in the uneven shape of the surface are approximately equal as described later. In this way, we believe that the unevenness on the outermost surface of the light diffusion (B) side is gentle, the surface area of the unevenness can be reduced and the back reflection can be suppressed, so the light loss will be reduced and the light transmittance will be improved. Get bigger.

The cross-sectional view of FIG. 1 shows an example of the structure of the light diffusion film of the present invention. As shown in the figure, the light diffusion film 10 has a light diffusion layer (B) 12 layered on an area of the transparent substrate (A) 11. The light diffusion layer (B) 12 contains particles 12b and a thixotropy imparting agent 12c in the resin layer 12a. The resin layer 12a is formed of a binder resin. The particles 12b and the thixotropy imparting agent 12c are fillers. The surface of the light diffusion layer (B) 12 opposite to the transparent base material (A) 11 has irregularities. The uneven shape satisfies the aforementioned mathematical formula (1) (0.110≦Sm) and the aforementioned mathematical formula (2) (Rsk≦0.200). However, the light diffusion film of the present invention is not limited to this. For example, the particles 12b and the thixotropy imparting agent 12c are optional.

In addition, the light-diffusion film of the present invention may be further laminated with another layer on the surface of the light-diffusion layer (B) opposite to the transparent base material (A) as described above. However, the aforementioned other layers may or may not exist. When the aforementioned other layers are present, the aforementioned other layers may be, for example, an adhesive layer, an adhesive layer, a low refractive index layer, a high refractive index layer, a conductive layer, a UV absorption layer, an antifouling layer, a high hardness layer, a stress relaxation layer, Undercoat etc. The aforementioned other layer may be one layer or multiple layers, and when multiple layers, there may be one type or multiple types. For example, the aforementioned other layer may be an optical film whose thickness and refractive index are strictly controlled, or may be a laminate of two or more layers of the aforementioned optical film.

In addition, in the light diffusion film of the present invention, "the outermost surface on the light diffusion layer (B) side" is the outermost surface on the light diffusion layer (B) side. Specifically, "the outermost surface on the side of the light diffusion layer (B)" is the side of the light diffusion layer (B) opposite to the transparent substrate (A) when the other layers are not present (for example, FIG. 1) surface. In addition, "the outermost surface on the light diffusion (B) side", when the other layer (not shown) is present, is the outermost surface of the other layer on the side opposite to the transparent substrate (A).

In the present invention, Sm in the aforementioned formula (1) represents the average amount of the length of the contour curve element in the reference length. The Sm of the aforementioned mathematical formula (1) is the amount measured in accordance with JIS B0601 (1994 edition) as described above, and can be measured, for example, by the method described in the following examples.

In the light diffusion film of the present invention, the uneven shape Sm of the outermost surface on the light diffusion layer (B) side is 0.110 or more as shown in the above formula (1), for example, it may be 0.120 or more, 0.130 or more, or 0.140 or more. The upper limit of Sm is not particularly limited, and is, for example, 0.200 or less.

In the present invention, Rsk (skewness) of the aforementioned mathematical formula (2) is the cubic average of Z(x) in the reference length after the root-mean-square height Rq is non-dimensioned. In addition, the so-called skewness means skewness, which indicates the symmetry between the peak and the valley when the average line is the center. If Rsk=0, it is symmetrical with respect to the average line (normal distribution). If Rsk>0, it will be lower than the average line, and if Rsk<0, it will be higher than the average line. The aforementioned mathematical formula (2) Rsk is the amount measured in accordance with JIS B0601 (1994 edition) as described above, and can be measured, for example, by the method described in the following examples.

In the light-diffusing film of the present invention, Rsk of the concave-convex shape on the outermost surface of the light-diffusing layer (B) side is 0.200 or less as shown in the above mathematical formula (2), for example, it may be 0.180 or less, 0.160 or less or 0.120 the following. The lower limit of Rsk is not particularly limited, and is, for example, -0.200 or more.

In the light diffusion film of the present invention, the ten-point average roughness (also called ten-point average height) Rz of the uneven shape on the outermost surface of the light diffusion layer (B) side may be, for example, 1.700 or less, 1.200 or less, or 1.000 or less Or below 0.900. The lower limit of Rz is not particularly limited, and may be 0.200 or more, for example. With the aforementioned smaller Rz, higher light transmittance can be easily obtained. The aforementioned Rz can be measured, for example, by the measuring method described in the following Examples. The aforementioned Rz can be expressed by the sum of the average from the height of the largest peak of the contour curve to the fifth and the average from the depth of the lowest valley to the fifth in the reference length, for example.

In the present invention, the light transmittance of the light diffusion film can be represented by the aforementioned visual transmittance loss rate (the visual transmittance loss rate at a wavelength of 380 to 780 nm), for example. The aforementioned visual transmittance loss rate can be expressed as the visual transmittance loss rate with respect to the light-transmitting substrate. The aforementioned light-transmitting substrate is, for example, a transparent plastic film substrate, and the light diffusion film of the present invention is the transparent substrate (A). The aforementioned visual transmittance loss rate can make the visual transmittance loss rate Y of only the light-transmitting substrate Y1, and the visual transmittance loss rate Y of the light-diffusing film Y2, which can be calculated according to the following mathematical formula Figure out. In addition, the aforementioned visual transmittance loss rate can be measured and calculated, for example, by the measurement method and calculation method described in the examples described later. In addition, the aforementioned visual transmittance loss rate is not particularly limited. For example, it may be 3.0% or less, or 2.5% or less or 2.0% or less as described above. The lower limit of the aforementioned visual transmittance loss rate is not particularly limited, and may be, for example, 0% or a value greater than 0%. Visual transmittance loss rate (%)=(Y1-Y2)/Y1×100

The overall haze value of the light diffusion film of the present invention is not particularly limited. For example, it can be 10% or more, 15% or more, 18% or more, or 20% or more, or it can be, for example, 40% or less, 35% or less, or 32% or less. Or less than 28%. If the overall haze value is high, the light diffusibility is likely to increase. If the overall haze value is low, the light transmittance is likely to increase. In addition, the haze value is an index related to transparency of optical films and the like, and represents haze (opacity). In addition, the haze value can be calculated from the ratio of diffuse transmitted light to total light transmitted light, and it is affected by surface roughness and the like. The overall haze value of the light-diffusion film of the present invention can be defined by, for example, the following mathematical formula, and can be measured by, for example, the measurement method described in the following examples. Overall haze value (%)=Td/Tt×100 Td: diffuse transmittance Tt: total light transmittance

Hereinafter, the transparent base material (A), the light diffusion layer (B), and the other layers are further illustrated.

The aforementioned transparent substrate (A) is not particularly limited, and examples thereof include transparent plastic film substrates. The aforementioned transparent plastic film substrate is not particularly limited. It is preferable to have good light transmittance of visible light (preferably 90% or more of light transmittance) and good transparency (preferably one with haze value below 1%). Such as the transparent plastic film substrate described in Japanese Patent Laid-Open No. 2008-90263. The forming material of the aforementioned transparent plastic film substrate specifically includes polyester-based polymers such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and cellulose diacetate (DAC). , Cellulose polymers such as cellulose triacetate (TAC), polycarbonate polymers, acrylic polymers such as polymethyl methacrylate, etc. In addition, the forming material of the transparent plastic film substrate may include, for example, polystyrene, styrene-based polymers such as acrylonitrile-styrene copolymer, polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, Olefin-based polymers such as ethylene-propylene copolymers, vinyl chloride-based polymers, and amide-based polymers such as nylon or aromatic polyamides. In addition, the material for forming the transparent plastic film substrate may include, for example, imine-based polymers, turbidity-based polymers, polyether turbidity-based polymers, polyether ether ketone-based polymers, polyphenylene sulfide-based polymers, Vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, aryl ester polymer, polyoxymethylene polymer, epoxy polymer, or a mixture of the foregoing polymers, etc. The aforementioned transparent plastic film substrate can be suitably used with less optical birefringence. The light diffusion film of the present invention can also be used as a protective film for polarizing plates. In this case, the transparent plastic film substrate is preferably made of polyethylene terephthalate (PET), cellulose triacetate (TAC), Films formed of polycarbonate, acrylic polymer, polyolefin with cyclic or norbornene structure, etc. Furthermore, in the present invention, as described later, the aforementioned transparent plastic film substrate may also be the polarizer itself. With the above configuration, the structure of the polarizing plate can be simplified without a protective layer made of TAC or the like. Therefore, the number of manufacturing steps of the polarizing plate or the image display device can be reduced, and the production efficiency can be improved. Moreover, as long as it has the above configuration, the polarized light can be made thinner. In addition, when the transparent plastic film substrate is a polarizer, the light diffusion layer (B) and the low reflection layer (C) will function as protective layers. Moreover, as long as it has the above-mentioned configuration, the light-diffusion film will also function as a cover plate when it is attached to the surface of a liquid crystal cell, for example.

In the present invention, the thickness of the aforementioned transparent substrate (A) is not particularly limited. If considering the strength, handleability and other workability and thinness, for example, it is 10~500μm, 20~300μm or 30~200μm. range. The refractive index of the aforementioned transparent substrate (A) is not particularly limited. The aforementioned refractive index is, for example, in the range of 1.30 to 1.80 or 1.40 to 1.70.

The light diffusion film of the present invention is as described above, and the transparent substrate (A) may also contain acrylic resin.

In addition, the light diffusion film of the present invention is, for example, as described above, and the transparent substrate (A) may also be an acrylic film. At this time, the acrylic film forming the aforementioned transparent substrate (A) may also contain resins other than acrylic resin. The content rate of the acrylic resin contained in the transparent substrate (A) is not particularly limited. For example, it can be 80% by mass or more, 85% by mass or more, or 90% by mass or more, and the upper limit is not particularly limited, for example, 100% by mass. Less than 95% by mass.

In the light diffusion film of the present invention, for example, the aforementioned light diffusion layer (B) may also contain a resin (binder resin) and a filler. The aforementioned filler may also include at least one of particles and a thixotropic agent.

For example, when the light diffusion layer (B) contains no particles and contains a thixotropy imparting agent, the light diffusion film of the present invention can be produced in which the Sm and Rsk are small and the unevenness of the outermost surface is gentle. In addition, since the light diffusion layer (B) contains a thixotropy imparting agent and particles with a small particle size, the light diffusion film of the present invention with small Sm and Rsk and gentle unevenness on the outermost surface can also be obtained.

In the light-diffusing film of the present invention, for example, the resin contained in the light-diffusing layer (B) may also include an acrylic resin (also referred to as acrylic resin).

In the light diffusion film of the present invention, for example, the resin contained in the light diffusion layer (B) may also include a urethane acrylate resin.

In the light-diffusion film of the present invention, for example, the resin contained in the light-diffusion layer (B) may be a copolymer of a hardened urethane acrylate resin and a multifunctional acrylate.

In the light diffusion film of the present invention, for example, the light diffusion layer (B) is formed using a light diffusion layer forming material containing resin and filler, and the light diffusion layer (B) may have an agglomerated portion, and the agglomerated portion is formed by The filler aggregates to form a convex portion on the surface of the light diffusion layer (B). In addition, in the agglomerated portion that forms the convex portion, the filler may be present in a state where a plurality of fillers are gathered in one direction of the plane direction of the light diffusion layer (B). For the image display device of the present invention, for example, the light diffusion film of the present invention may be arranged such that one direction of the plurality of fillers is aligned with the longitudinal direction of the black matrix pattern.

In the light diffusion film of the present invention, the aforementioned thixotropy imparting agent may also be at least one selected from the group consisting of organoclay, oxidized polyolefin, and modified urea. In addition, the aforementioned thixotropy imparting agent may be, for example, a tackifier.

In the light diffusion film of the present invention, the thixotropy imparting agent is preferably contained in the range of 0.2 to 5 parts by weight relative to 100 parts by weight (mass) of the resin of the light diffusion layer (B).

In the light-diffusing film of the present invention, the particles may be included in the range of 0.2-12 parts by weight or 0.5-12 parts by weight with respect to 100 parts by weight of the resin of the light-diffusing layer (B).

In the method of manufacturing the light diffusion film of the present invention, the surface shape of the light diffusion film can be adjusted by adjusting the weight parts of the particles in the light diffusion layer forming material relative to 100 parts by weight of the resin.

By having the agglomerated part formed by agglomerating particles, for example, the light-diffusing film of the present invention can be made into the light-diffusing film of the present invention whose uneven shape is gentle. Moreover, for example, by having the agglomerated portion, the average distance between unevenness Sm (mm) on the surface of the light diffusion layer (B) becomes larger. The light diffusion film with the surface shape can effectively prevent the reflection of fluorescent lamps and the like. However, the light diffusion film of the present invention is not limited by this.

The light diffusion layer (B) is, for example, as described later, a coating film is formed by applying a coating solution containing the resin, the filler, and the solvent to at least one surface of the transparent substrate (A), and then the coating The film is formed by removing the aforementioned solvent. Examples of the aforementioned resin include thermosetting resin and free radiation curable resin that can be cured by ultraviolet light or light. As the aforementioned resin, commercially available thermosetting resins or ultraviolet curing resins can also be used.

As the aforementioned thermosetting resin or ultraviolet curing resin, for example, a curing compound having at least one of an acrylate group and a methacrylate group that can be cured by heat, light (ultraviolet rays, etc.), or electron beams can be used. Examples include silicone resins, polyester resins, polyether resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and polyols. Polyfunctional compounds such as oligomers or prepolymers such as acrylate or methacrylate. These may be used individually by 1 type, and may use 2 or more types together.

For the aforementioned resin, for example, a reactive diluent having at least one of an acrylate group and a methacrylate group may be used. As the aforementioned reactive diluent, for example, the reactive diluent described in JP 2008-88309 A can be used. For example, it includes monofunctional acrylate, monofunctional methacrylate, multifunctional acrylate, and multifunctional methacrylate. . The aforementioned reactive diluent is preferably trifunctional or higher acrylate and trifunctional or higher methacrylate. This is because the hardness of the light diffusion layer (B) can be excellent. The reactive diluent may also include, for example, butylene glycol glyceryl ether diacrylate, acrylate of isocyanuric acid, and methacrylate of isocyanuric acid. These may be used individually by 1 type, and may use 2 or more types together.

The main function of the particles used to form the light diffusion layer (B) is to make the surface of the light diffusion layer (B) formed into a concave-convex shape to impart light diffusibility and control the fog of the light diffusion layer (B). Degree value. The haze value of the light diffusion layer (B) can be designed by controlling the refractive index difference between the particles and the resin. The refractive index difference between the aforementioned particles and the aforementioned resin is not particularly limited. For example, as mentioned above, it can be 0.200 or less, 0.150 or less, 0.100 or less, or 0.050 or less, and for example, it can be 0 or more, can be a value greater than 0, or can be Above 0.010, above 0.020, or above 0.030. Examples of the aforementioned particles include inorganic particles and organic particles. The aforementioned inorganic particles are not particularly limited, and examples thereof include silica particles, titanium oxide particles, alumina particles, zinc oxide particles, tin oxide particles, calcium carbonate particles, barium sulfate particles, talc particles, kaolin particles, calcium sulfate particles, and the like. Furthermore, the aforementioned organic particles are not particularly limited, and examples include polymethyl methacrylate resin powder (PMMA particles), polysiloxane resin powder, polystyrene resin powder, polycarbonate resin powder, acrylic styrene resin powder, Benguanamine resin powder, melamine resin powder, polyolefin resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, polyvinyl fluoride resin powder, etc. These inorganic particles and organic particles may be used alone or in combination of two or more kinds.

The particle diameter (D) (weight average particle diameter) of the aforementioned particles is not particularly limited, and is, for example, in the range of 2-10 μm. By setting the weight average particle diameter of the aforementioned particles in the aforementioned range, for example, a light-diffusing film with better light diffusibility and suppressed reflection can be produced. From the viewpoint of restraining the reflection from the oblique direction, the weight average particle size of the aforementioned particles should not be too small. From the viewpoint of suppressing reflection from the front direction, the weight average particle size of the aforementioned particles should not be too large. The weight average particle diameter of the aforementioned particles can be, for example, 2.2 μm or more, 2.3 μm or more, 2.5 μm or more, or 3.0 μm or more, and can be 9.0 μm or less, 8.0 μm or less, 7.0 μm or less, or 6.0 μm or less. The weight average particle diameter of the aforementioned particles can be, for example, 2.2 μm or more and 9.0 μm or less, 2.2 μm or more and 8.0 μm or less, 2.2 μm or more and 7.0 μm or less, 2.2 μm or more and 6.0 μm or less, 2.3 μm or more and 9.0 μm or less, 2.3 μm or more and 8.0 μm or less, 2.3 μm or more and 7.0 μm or less, 2.3 μm or more and 6.0 μm or less, 2.5 μm or more and 9.0 μm or less, 2.5 μm or more and 8.0 μm or less, 2.5 μm or more and 7.0 μm or less, 2.5 μm Above and 6.0 μm or less, 3.0 μm or more and 9.0 μm or less, 3.0 μm or more and 8.0 μm or less, 3.0 μm or more and 7.0 μm or less, or 3.0 μm or more and 6.0 μm or less. In addition, the weight average particle size of the aforementioned particles can be measured by, for example, the Coulter counting method. For example, a particle size distribution measuring device (trade name: Coulter Multisizer, manufactured by Beckman Coulter, Inc.) using the pore resistance method is used to measure the resistance of the electrolyte solution corresponding to the particle volume when the particles pass through the pores. The number and volume of the aforementioned particles are calculated to calculate the weight average particle size.

The shape of the aforementioned particles is not particularly limited. For example, it may be roughly spherical in the form of beads, or amorphous, such as powder, but it is preferably roughly spherical, more preferably roughly spherical particles with an aspect ratio of 1.5 or less, and most preferably For spherical particles.

The ratio of the particles in the light diffusion layer (B) to 100 parts by weight of the resin may be, for example, 0.1 parts by weight or more, 0.2 parts by weight or more, 0.3 parts by weight or more, or 0.5 parts by weight or more, and may be 10 parts by weight or less , 8 parts by weight or less, 7 parts by weight or less, or 6 parts by weight or less. The ratio of the aforementioned particles relative to 100 parts by weight of the aforementioned resin may be, for example, 0.1 parts by weight or more and 10 parts by weight or less, 0.1 parts by weight or more and 8 parts by weight or less, 0.1 parts by weight or more and 7 parts by weight or less, 0.1 parts by weight or more, and 6 parts by weight or less, 0.2 parts by weight or more and 10 parts by weight or less, 0.2 parts by weight or more and 8 parts by weight or less, 0.2 parts by weight or more and 7 parts by weight or less, 0.2 parts by weight or more and 6 parts by weight or less, 0.3 parts by weight or more, and 10 parts by weight or less, 0.3 parts by weight or more and 8 parts by weight or less, 0.3 parts by weight or more and 7 parts by weight or less, 0.3 parts by weight or more and 6 parts by weight or less, 0.5 parts by weight or more and 10 parts by weight or less, 0.5 parts by weight or more, and 8 parts by weight or less, 0.5 parts by weight or more and 7 parts by weight or less, or 0.5 parts by weight or more and 6 parts by weight or less. By setting the ratio of the aforementioned particles to the aforementioned range, for example, the aforementioned agglomerated portion can be suitably formed, and for example, a light-diffusing film having better light diffusibility and suppressed reflection can be produced.

In the light diffusion layer (B), the filler may be particles and a thixotropy imparting agent. The aforementioned thixotropy imparting agent may be contained alone, or the aforementioned thixotropy imparting agent may be further contained in addition to the aforementioned particles. By including the thixotropy imparting agent, the aggregation state of the particles can be easily controlled. Examples of the aforementioned thixotropy imparting agent include organoclay, oxidized polyolefin, and modified urea.

The aforementioned organic clay is preferably a layered clay that has been organically treated in order to improve the affinity with the aforementioned resin. The aforementioned organic clay can be prepared in-house or commercially available. The aforementioned commercially available products include, for example, LOOSENTIGHT SAN, LOOSENTIGHT STN, LOOSENTIGHT SEN, LOOSENTIGHT SPN, SOMASIF ME-100, SOMASIF MAE, SOMASIF MTE, SOMASIF MEE, SOMASIF MPE (trade names, all are Co-op Chemical Co., Ltd. ESBEN, ESBEN C, ESBEN E, ESBEN W, ESBEN P, ESBEN WX, ESBEN N-400, ESBEN NX, ESBEN NX80, ESBEN NO12S, ESBEN NEZ, ESBEN NO12, ESBEN NE, ESBEN NZ, ESBEN NZ70, ORGANITE , ORGANITE D, ORGANITE T (trade names, all manufactured by HOJUN Co., Ltd.); KUNIPIA F, KUNIPIA G, KUNIPIA G4 (trade names, all manufactured by KUNIMINE INDUSTRIES CO., LTD.); TIXOGEL VZ, CLAYTONE HT , CLAYTONE 40 (trade names, all manufactured by Rockwood Additives Ltd), etc.

The aforementioned oxidized polyolefin can be prepared in-house or commercially available. Examples of the aforementioned commercially available products include DISPARLON 4200-20 (trade name, manufactured by Kusumoto Chemical Co., Ltd.), DISPARLON SA300 (trade name, manufactured by Kyoeisha Chemical Co., Ltd.), and the like.

The reaction product of the aforementioned modified urea isocyanate monomer or its adduct and an organic amine. The aforementioned modified urea can be prepared in-house or commercially available. Examples of the aforementioned commercially available products include BYK410 (manufactured by BYK-CHEMIE).

The said thixotropy imparting agent may be used individually by 1 type, and may use 2 or more types together.

The ratio of the thixotropy imparting agent in the light diffusion layer (B) is preferably in the range of 0.2 to 5 parts by weight, and more preferably in the range of 0.4 to 4 parts by weight relative to 100 parts by weight of the resin.

The maximum thickness (d') of the aforementioned light diffusion layer (B) is not particularly limited, but is preferably within the range of 3-12 µm. By setting the maximum thickness (d') of the light-diffusion layer (B) in the aforementioned range, for example, the light-diffusion film can be prevented from curling, and problems such as poor transportability and reduced productivity can be avoided. Moreover, when the aforementioned thickness (d) falls within the aforementioned range, the weight-average particle size (D) of the aforementioned particles is preferably within the range of 2-10 μm as mentioned above. By combining the maximum thickness (d') of the light diffusion layer (B) and the weight average particle size (D) of the particles as described above, a light diffusion film with excellent light diffusion properties can be produced. The maximum thickness (d') of the aforementioned light diffusion layer (B) is more preferably in the range of 3-8µm.

The ratio D/d of the thickness (d') of the light diffusion layer (B) to the weight average particle diameter (D) of the particles may be, for example, 1 or less, 0.9 or less, 0.8 or less, 0.7 or less, or 0.6 or less, and may be 0.1 or more, 0.2 or more, 0.3 or more, or 0.4 or more. The aforementioned D/d may be, for example, 0.1 or more and 1 or less, 0.2 or more and 1 or less, 0.3 or more and 1 or less, 0.4 or more and 1 or less, 0.1 or more and 0.9 or less, 0.2 or more and 0.9 or less, 0.3 or more and 0.9 or less, 0.4 Above and below 0.9, above 0.1 and below 0.8, 0.2 above and below 0.8, below 0.3 and below 0.8, above 0.4 and below 0.8, above 0.1 and below 0.7, above 0.2 and below 0.7, above 0.3 and below 0.7, above 0.4 and 0.7 or less, 0.1 or more and 0.6 or less, 0.2 or more and 0.6 or less, 0.3 or more and 0.6 or less, or 0.4 or more and 0.6 or less. By having the above relationship, a light diffusing film with better light diffusivity and suppressed reflection can be made.

In the light-diffusing film of the present invention, for example, the light-diffusion layer (B) has an agglomerated portion, and the agglomerated portion forms a convex portion on the surface of the light-diffusion layer (B) by agglomeration of the filler, thereby forming the convex shape In the agglomeration part of the part, the said filler may exist in the state in which a some filler was gathered in one direction of the surface direction of the said light-diffusion layer (B). By this, for example, the reflection of fluorescent lamps can be prevented. However, the light diffusion film of the present invention is not limited by this.

In addition, the light-diffusing film of the present invention may have an intermediate layer between the transparent substrate (A) and the light-diffusing layer (B), the intermediate layer containing a resin derived from the transparent substrate (A) and a source From the resin of the aforementioned light diffusion layer (B). By controlling the thickness of the intermediate layer, the surface shape of the aforementioned light diffusion layer (B) can be controlled. For example, when the thickness of the intermediate layer is increased, the Sm and Rsk tend to become larger, and when the thickness of the intermediate layer is reduced, the Sm and Rsk tend to become smaller. In addition, the presence of the aforementioned intermediate layer can be confirmed by observing the cross section of the light-diffusing film under a microscope, for example. In addition, the thickness of the intermediate layer, the transparent substrate (A), and the light diffusion layer (B) can be measured, for example, by observing the cross section of the light diffusion film with a microscope to identify the transparent substrate (A) and the intermediate Layer and the interface of the aforementioned light diffusion layer (B). The aforementioned microscope can be, for example, a Transmission Electron Microscope (TEM). In addition, for the identification of the aforementioned interface, for example, time-of-flight secondary ion mass spectrometry can also be used. The method can be used, for example, when it is difficult to use a specific interface of the microscope.

In the present invention, the mechanism for forming the aforementioned intermediate layer (also referred to as a permeable layer or a compatible layer) is not particularly limited. For example, it is formed in the aforementioned drying step in the manufacturing method of the light diffusion film of the present invention. Specifically, for example, in the drying step, the coating liquid for forming the light diffusion layer (B) penetrates the transparent substrate (A) to form a resin derived from the transparent substrate (A) and The aforementioned intermediate layer of the resin of the light diffusion layer (B). The resin contained in the intermediate layer is not particularly limited. For example, the resin contained in the transparent substrate (A) and the resin contained in the light diffusion layer (B) may be simply mixed (compatibly). In addition, in the resin contained in the intermediate layer, for example, at least one of the resin contained in the transparent substrate (A) and the resin contained in the light diffusion layer (B) may be chemically changed by heating, light irradiation, or the like.

The thickness ratio R of the aforementioned intermediate layer defined by the following formula (5) is not particularly limited. For example, it is 0.10 to 0.80. For example, it can be 0.15 or more, 0.20 or more, 0.25 or more, 0.30 or more, 0.40 or more, or 0.45 or more, and for example It can be 0.75 or less, 0.70 or less, 0.65 or less, 0.60 or less, 0.50 or less, 0.40 or less, 0.45 or less, or 0.30 or less. The aforementioned intermediate layer can be confirmed by observing the cross section of the light diffusion film with a transmission electron microscope (TEM), for example, and the thickness can be measured. The thickness of _{R = [D C / (D} C + D B)] (5) in the equation (5), D _B Department of the light diffusing layer (B) of [μm], a thickness D _C based the intermediate layer [µm].

In the light diffusion film of the present invention, for example, as described above, the light diffusion layer (B) has an agglomerated portion that is formed by forming a convex portion on the surface of the light diffusion layer (B) by agglomeration of the filler In the agglomerated portion of the convex portion, the filler may be present in a state where a plurality of fillers are gathered in one direction of the surface direction of the light diffusion layer (B). Thereby, the said convex part can be made into the gentle shape which has anisotropy. However, the light diffusion film of the present invention is not limited by this.

The surface shape of the light diffusion layer (B) can be arbitrarily designed by controlling the aggregation state of the filler contained in the light diffusion layer forming material. The aggregation state of the filler can be controlled by, for example, the material of the filler (such as the chemical modification state of the particle surface, the affinity for solvents or resins, etc.), the type and combination of resin (binder) or solvent, etc. In addition, the aggregation state of the particles can be precisely controlled by the thixotropy imparting agent. As a result, in the present invention, the surface shape of the light diffusion film can be controlled (adjusted) in a wide range. For example, the aggregation state of the filler can be made as described above, and the convex portion can be made into a gentle shape. In addition, it is also possible to control (adjust) the surface shape of the light diffusion film in a wider range by adjusting the weight parts of the particles in the light diffusion layer forming material relative to 100 parts by weight of the resin as described above.

In addition, the light-diffusing film of the present invention may also be one in which the convex portion has a gentle shape to prevent the occurrence of protrusions on the light-diffusing (B) surface that cause appearance defects, but it is not limited thereto. In addition, in the light-diffusion film of the present invention, for example, a plurality of the aforementioned particles may be present in the position where the light-diffusion layer (B) overlaps directly or indirectly in the thickness direction.

The aforementioned other layers are not particularly limited. For example, as mentioned above, they may also be adhesive layers, adhesive layers, low refractive index layers, high refractive index layers, conductive layers, UV absorption layers, antifouling layers, high hardness layers, and stress relaxation layers. , Undercoat, etc. In addition, the aforementioned other layer may be one layer or multiple layers, and when multiple layers, there may be one type or multiple types. For example, the aforementioned other layer may be an optical film whose thickness and refractive index are strictly controlled, or may be a laminate of two or more layers of the aforementioned optical film.

[2. Manufacturing method of light diffusion film] The manufacturing method of the light-diffusion film of the present invention is not particularly limited, and it can be manufactured by any method, but it is preferably manufactured by the aforementioned manufacturing method of the light-diffusion film of the present invention.

The manufacturing method of the said light-diffusion film can be performed in the following way, for example.

First, the light diffusion layer (B) is formed on the transparent substrate (A) so as to satisfy the mathematical formulas (1) and (2) (light diffusion layer (B) forming step). Thereby, the laminated body of the said transparent base material (A) and the said light-diffusion layer (B) is manufactured. The step of forming the light diffusion layer (B) is as described above, including: a coating step of applying a coating liquid on the transparent substrate (A); and a coating film forming step of drying the applied coating liquid To form a coating film. In addition, for example, as described above, the light diffusion layer (B) forming step may further include a curing step of curing the coating film. The aforementioned curing may be performed after the aforementioned drying, for example, but is not limited to this. The aforementioned curing can be performed by, for example, heating, light irradiation, or the like. The aforementioned light is not particularly limited, and may be, for example, ultraviolet rays. The light source for the aforementioned light irradiation is also not particularly limited, and may be, for example, a high-pressure mercury lamp.

The aforementioned coating liquid contains a resin and a solvent as described above. The coating liquid may be, for example, a light diffusion layer forming material (coating liquid) containing the resin, the particles, the thixotropy imparting agent, and the solvent.

The aforementioned coating liquid should exhibit thixotropy, and the Ti value specified by the following formula should be in the range of 1.3 to 3.5, more preferably in the range of 1.4 to 3.2, and more preferably in the range of 1.5 to 3. Ti value = β1/β2 In the above formula, β1 is the viscosity measured at a shear rate of 20 (1/s) using RheoStress RS6000 manufactured by HAAKE, and β2 is the viscosity measured at a shear rate of 200 (1/s) using RheoStress RS6000 manufactured by HAAKE. The measured viscosity.

As long as the Ti value is 1.3 or more, it is less likely to cause appearance defects, or deterioration of light diffusibility and white halo characteristics. In addition, as long as the Ti value is 3.5 or less, the aforementioned problems such as the particles are not agglomerated but are dispersed.

In addition, the aforementioned coating liquid may contain or not contain a thixotropy imparting agent, but it is preferably contained because it contains a thixotropy imparting agent because it can easily exhibit thixotropy. In addition, as described above, when the coating liquid contains the thixotropy imparting agent, the effect of preventing the sedimentation of the particles (thixotropy effect) can be obtained. In addition, the surface shape of the light diffusion film can be freely controlled in a wider range by shear aggregation of the thixotropy imparting agent itself. For example, when the coating liquid contains no particles and contains a thixotropy imparting agent, it is possible to produce the light diffusion film of the present invention with small Sm and Rsk and gentle unevenness on the outermost surface as described above. In addition, since the coating liquid contains a thixotropy imparting agent and particles with a small particle size, the light diffusion film of the present invention can be produced in which the Sm and Rsk are small and the unevenness of the outermost surface is gentle.

The aforementioned solvent is not particularly limited, and various solvents can be used, and one type may be used alone or two or more types may be used in combination. According to the composition of the aforementioned resin, the type and content of the aforementioned particles and the aforementioned thixotropy imparting agent, there is an optimal solvent type and solvent ratio in order to obtain the light diffusion film of the present invention. The solvent is not particularly limited, and examples include alcohols such as methanol, ethanol, isopropanol, butanol, and 2-methoxyethanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclopentanone. Classes; esters such as methyl acetate, ethyl acetate, and butyl acetate; ethers such as diisopropyl ether and propylene glycol monomethyl ether; glycols such as ethylene glycol and propylene glycol; ethyl cellulose, butyl cellulose, etc. Celluloids; aliphatic hydrocarbons such as hexane, heptane, and octane; aromatic hydrocarbons such as benzene, toluene, and xylene. Moreover, for example, the aforementioned solvent may also contain a hydrocarbon solvent and a ketone solvent. The aforementioned hydrocarbon solvent may be, for example, an aromatic hydrocarbon. The aforementioned aromatic hydrocarbon may be, for example, at least one selected from the group consisting of toluene, o-xylene, meta-xylene, p-xylene, ethylbenzene, and benzene. The aforementioned ketone solvent may be selected from the group consisting of cyclopentanone and acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, cyclohexanone, isophorone, and acetophenone, for example. At least one of them. The aforementioned solvent may be, for example, a solvent in which the aforementioned hydrocarbon solvent and the aforementioned ketone solvent are mixed in a mass ratio of 90:10 to 10:90. The mass ratio of the aforementioned hydrocarbon solvent to the aforementioned ketone solvent may be, for example, 80:20-20:80, 70:30-30:70, or 40:60-60:40. In this case, for example, the aforementioned hydrocarbon solvent is toluene, and the aforementioned ketone solvent may be cyclopentanone.

For example, when an acrylic film is used for the transparent substrate (A) to form the intermediate layer (permeation layer), a good solvent for the acrylic film (acrylic resin) can be suitably used. The solvent may be a solvent containing a hydrocarbon solvent and a ketone solvent as described above. The aforementioned hydrocarbon solvent may be, for example, an aromatic hydrocarbon. The aforementioned aromatic hydrocarbon may be, for example, at least one selected from the group consisting of toluene, o-xylene, meta-xylene, p-xylene, ethylbenzene, and benzene. The aforementioned ketone solvent may be selected from the group consisting of cyclopentanone, acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, cyclohexanone, isophorone, and acetophenone, for example. At least one of them. The aforementioned solvent may be, for example, a solvent in which the aforementioned hydrocarbon solvent and the aforementioned ketone solvent are mixed in a mass ratio of 90:10 to 10:90. The mass ratio of the aforementioned hydrocarbon solvent to the aforementioned ketone solvent may be, for example, 80:20-20:80, 70:30-30:70, or 40:60-60:40. In this case, for example, the aforementioned hydrocarbon solvent is toluene, and the aforementioned ketone solvent may be cyclopentanone.

In addition, by appropriately selecting the solvent, when the thixotropy imparting agent is contained, the thixotropy with respect to the light diffusion layer forming material (coating liquid) can be exhibited well. For example, when organoclay is used, toluene and xylene can be used alone or in combination; for example, when oxidized polyolefin is used, methyl ethyl ketone, ethyl acetate, propylene glycol monomethyl ether can be used alone or in combination; for example, modified In the case of urea, butyl acetate and methyl isobutyl ketone can be used alone or in combination.

Various leveling agents can be added to the aforementioned light diffusion layer forming material. For the aforementioned leveling agent, for example, a fluorine-based or silicone-based leveling agent can be used in order to prevent uneven application (uniform application surface). In the present invention, when antifouling properties are required for the surface of the light diffusion layer (B), or when a low reflection layer (low refractive index layer) or a layer containing an interlayer filler is formed on the light diffusion layer (B) as described later Wait for the situation, choose the leveling agent appropriately. In the present invention, the coating liquid can exhibit thixotropy by, for example, containing the aforementioned thixotropy imparting agent. Therefore, uneven coating is less likely to occur. At this time, for example, it will have the advantage of expanding the options of the aforementioned leveling agent.

The blending amount of the aforementioned leveling agent is not particularly limited, and it is preferably 0.3 to 5 parts by weight, more preferably 0.5 to 5 parts by weight relative to 100 parts by weight of the aforementioned resin.

Pigments, fillers, dispersants, plasticizers, ultraviolet absorbers, surfactants, antifouling agents, antioxidants, etc. can also be added to the aforementioned light diffusion layer forming materials according to needs within a range that does not impair performance. These additives may be used individually by 1 type, and may use 2 or more types together.

For the light diffusion layer forming material, for example, conventionally known photopolymerization initiators described in JP 2008-88309 A can be used.

The method of applying the aforementioned coating liquid on the aforementioned transparent substrate (A) to form a coating film can use, for example, a jet coating method, a die coating method, a spin coating method, a spray coating method, a gravure coating method, and a roll coating method. , Bar coating method and other coating methods.

Next, the aforementioned coating film is dried and hardened as described above to form the light diffusion layer (B). The aforementioned drying can be, for example, natural drying, air drying by spraying, heating drying, or a combination of these methods.

The drying temperature of the coating liquid for forming the light diffusion layer (B) may be in the range of, for example, 30 to 200°C. The aforementioned drying temperature may be, for example, 40°C or higher, 50°C or higher, 60°C or higher, 70°C or higher, 80°C or higher, 90°C or higher, or 100°C or higher, and may be 190°C or lower, 180°C or lower, 170°C or lower, 160 Below ℃, below 150℃, below 140℃, below 135℃, below 130℃, below 120℃ or below 110℃. The drying time is not particularly limited. For example, it can be 30 seconds or more, 40 seconds or more, 50 seconds or more, or 60 seconds or more, and can be 150 seconds or less, 130 seconds or less, 110 seconds or less, or 90 seconds or less.

The curing method of the aforementioned coating film is not particularly limited, but ultraviolet curing is preferred. The radiation amount of the energy ray source should be 50~500mJ/cm ^{2 in terms} of the cumulative exposure under the ultraviolet wavelength of 365nm. As long as the irradiation amount is 50 mJ/cm ² or more, the curing can be easily performed sufficiently, and the hardness of the formed light diffusion layer (B) is likely to increase. Moreover, as long as it is 500 mJ/cm ² or less, it is possible to prevent the formed light diffusion layer (B) from coloring.

According to the above procedure, a laminate of the transparent substrate (A) and the light diffusion layer (B) can be manufactured. This laminate can be used directly as the light diffusion film of the present invention. For example, the other layer may be formed on the light diffusion layer (B) to make the light diffusion film of the present invention. The method of forming the aforementioned other layer is not particularly limited, and for example, it can be performed in the same manner as or in accordance with the method of forming a general optical layer or the like.

According to the above procedure, the light diffusion film of the present invention with the light diffusion layer (B) layered on at least one area of the transparent substrate (A) can be manufactured. In addition, the light-diffusion film of the present invention may contain layers other than the transparent substrate (A) and the light-diffusion layer (B) as described above.

In addition, in the manufacturing step of the anti-reflection film of the present invention, it is preferable to perform surface treatment on at least one of the transparent substrate (A) and the light diffusion layer (B). As long as the surface of the transparent substrate (A) is surface-treated, the adhesion to the light diffusion layer (B) or the polarizer or the polarizer can be further improved. Moreover, as long as the surface of the light diffusion layer (B) is surface-treated, for example, the adhesion with the other layers can be further improved.

[3. Optical component and image display device] The optical member of this invention is not specifically limited, For example, it may be a polarizing plate. The aforementioned polarizing plate is also not particularly limited. For example, it may include the light diffusion film and polarizer of the present invention, and may further include other components. The constituent elements of the aforementioned polarizing plate can be bonded by, for example, an adhesive or an adhesive.

The image display device of the present invention is also not particularly limited, and may be any image display device, such as a liquid crystal display device, an organic EL display device, a quantum dot display device, and the like.

As mentioned above, the light diffusion film of the present invention can also be used on the back side of the display panel for image display devices. Specifically, for example, the light diffusion film of the present invention can be attached to the visible back side of the display panel for image display devices by means of an adhesive or an adhesive. In this case, the light-diffusing film of the present invention can be used alone, for example, or as an optical member of the present invention including other constituent elements (for example, the aforementioned polarizing plate, etc.). In addition, the image display device of the present invention may include, for example, the aforementioned display panel for the image display device and the backlight for the image display device. Specifically, for example, the light diffusion film of the present invention or the optical member of the present invention may be attached to the visible back side of the display panel for the image display device, and on the visible back side of the display panel for the image display device It is equipped with the aforementioned backlight for the image display device. In the light diffusion film of the present invention, as described above, the concave-convex shape on the outermost surface of the light diffusion layer (B) side is gentle. Therefore, according to the light diffusion film of the present invention, for example, it is possible to suppress or prevent damage to the surface of the backlight for the image display device caused by the uneven shape. However, the image display device of the present invention is not limited by this.

The image display device of the present invention is, for example, an image display device having the light diffusion film of the present invention on the surface of the viewing side, and the aforementioned image display device may also have a black matrix pattern.

The light-diffusing film of the present invention can, for example, bond the transparent substrate (A) side to an optical member that can be used for LCD through an adhesive or adhesive. In addition, during the bonding, the surface of the transparent substrate (A) may be subjected to various surface treatments as described above. As mentioned above, according to the method of manufacturing the light diffusion film of the present invention, the surface shape of the light diffusion film can be freely controlled in a wide range. Therefore, the optical characteristics that can be obtained by laminating the aforementioned light diffusion film with other optical components using adhesives, adhesives, etc. cover a wide range that corresponds to the surface shape of the aforementioned light diffusion film.

Examples of the aforementioned optical member include a polarizer or a polarizing plate. The composition of the polarizing plate is generally that the polarizer has a transparent protective film on one or both sides. When a transparent protective film is to be provided on both sides of the polarizer, the transparent protective film on the front and back can be the same material or different materials. Polarizing plates are usually arranged on both sides of the liquid crystal cell. In addition, the polarizing plates are arranged so that the absorption axes of the two polarizing plates are approximately orthogonal to each other.

The structure of the polarizing plate laminated with the light diffusion film is not particularly limited. For example, it may be a structure in which a transparent protective film, the polarizer and the transparent protective film are sequentially laminated on the light diffusion film, or the light On the diffusion film, the polarizer and the transparent protective film are laminated in this order.

The image display device of the present invention has the same structure as the conventional image display device except for the light diffusion film. For example, in the case of an LCD, it can be manufactured in the following manner: the optical components such as the liquid crystal cell, the polarizing plate, and the lighting system (backlight, etc.) according to the needs are properly assembled, and then the drive circuit is incorporated.

The image display device of the present invention can be used for any appropriate purpose. Its uses are, for example, computer monitors, notebook computers, copiers and other OA equipment, mobile phones, clocks, digital cameras, portable information terminals (PDAs), portable game consoles and other portable devices, video cameras, TVs, microwave ovens, etc. Household electrical equipment, backlight monitors, monitors for car navigation systems, automotive equipment such as car audio, display equipment such as information guide screens for commercial stores, security equipment such as monitoring screens, nursing monitors, medical applications Monitors and other nursing medical equipment, etc. Example

Next, examples of the present invention will be described together with comparative examples. However, the present invention is not limited by the following Examples and Comparative Examples.

[Example 1] Mix 60 parts by weight of neopentyl erythritol triacrylate (PETA; manufactured by Osaka Organic Chemical Co., Ltd., trade name "Viscoat #300") as a binder resin and urethane acrylate prepolymer (manufactured by Shinnakamura Chemical Industry Co., Ltd.) , Trade name "UA-53H-80BK") 40 parts by weight, silicone particles (manufactured by Momentive Performance Materials Co., Ltd., trade name "Tospearl 130", weight average particle size: 3µm, |D90-D50|: 2.5µm) 4 parts by weight of organic clay synthetic bentonite (manufactured by KUNIMINE INDUSTRIES CO., LTD., trade name "SUMECTON SAN") 2.5 parts by weight, photopolymerization initiator (manufactured by BASF, trade name "IRGACURE 907") 5 parts by weight and 1.0 part by weight of a leveling agent (manufactured by DIC, trade name "PC4100", solid content 10%), and toluene/cyclopentanone (CPN) mixed solvent (weight ratio toluene/cyclopentanone=70/ 30) Dilute to prepare a composition I for forming a light diffusion layer having a solid content of 31.5% by weight. In addition, the aforementioned organoclay system was diluted with toluene to a solid content of 6% by weight and then used.

And use a wire rod to apply the above-mentioned composition I for forming a light diffusion layer on a transparent plastic film substrate (acrylic film, manufactured by Toyo Kohan Co., Ltd., trade name "HX-40UC", thickness: 40 µm, refractive index: 1.50) , The visual transmittance loss rate of the monomer is 94.0%). After heating at 90°C for 1 minute, the high-pressure mercury lamp is used to irradiate ultraviolet light with a cumulative light quantity of 300mJ/cm ² . According to the above method, the following light diffusion film can be obtained: the light diffusion layer (B) (thickness 5.7µm) is layered on one area of the transparent substrate (A), and the transparent substrate (A) and the light diffusion layer (B) An intermediate layer is formed between the resin derived from the transparent substrate (A) and the resin derived from the light diffusion layer (B). In addition, the formation of the intermediate layer in this example and all the following examples and comparative examples was confirmed by observing the cross section of the light diffusion film with a transmission electron microscope (TEM).

[Example 2] A light diffusion film was obtained in the same manner as in Example 1, except that the light diffusion layer was formed to have a thickness of 6.3 μm.

[Example 3] A light diffusion film was obtained in the same manner as in Example 1, except that the light diffusion layer was formed to have a thickness of 6.9 μm.

[Example 4] A light diffusion film was obtained in the same manner as in Example 1, except that the light diffusion layer was formed to have a thickness of 7.3 μm.

[Example 5] A light-diffusion film was obtained in the same manner as in Example 1, except that the heating time after coating the composition I for forming a light-diffusion layer was changed from 1 minute to 30 seconds.

[Example 6] A light diffusion film was obtained in the same manner as in Example 5 except that the light diffusion layer was formed to have a thickness of 6.3 μm.

[Example 7] A light diffusion film was obtained in the same manner as in Example 5 except that the light diffusion layer was formed to have a thickness of 6.9 μm.

[Example 8] A light diffusion film was obtained in the same manner as in Example 5 except that the light diffusion layer was formed to have a thickness of 7.3 μm.

[Example 9] A PET film (manufactured by KOLON INDUSTRIES, trade name "ASTROLL CE900", thickness: 38 µm, refractive index: 1.64, and monomer transmittance loss rate of 88.3%) was used instead of the aforementioned acrylic film of Example 1 as a transparent plastic film A light diffusion film was obtained in the same manner as in Example 1 except for the substrate (transparent substrate (A)).

[Example 10] Use TAC (manufactured by Konica Minolta Co., Ltd., trade name "KC4UY", thickness: 40 µm, refractive index: 1.50, monomer transmittance loss rate of 92.4%) instead of the aforementioned acrylic film in Example 1 as the transparent plastic film base A light-diffusing film was obtained in the same manner as in Example 1 except for the transparent substrate (A).

[Comparative Example 1] Mix 60 parts by weight of neopentyl erythritol triacrylate (PETA; manufactured by Osaka Organic Chemical Co., Ltd., trade name "Viscoat #300") as a binder resin and urethane acrylate prepolymer (manufactured by Shinnakamura Chemical Industry Co., Ltd.) , Brand name "UA-53H-80BK") 40 parts by weight, organic particles (manufactured by Sekisui Chemicals Industry Co., Ltd., brand name "SSX1055QXE", weight average particle size: 5.5 µm) 4 parts by weight, organic clay synthetic bentonite (Manufactured by KUNIMINE INDUSTRIES CO., LTD., trade name "SUMECTON SAN") 2.5 parts by weight, photopolymerization initiator (manufactured by BASF, trade name "IRGACURE 907") 5 parts by weight, and leveling agent (manufactured by DIC, Product name "PC4100", solid content 10%) 1.0 parts by weight, and diluted with toluene/methyl ethyl ketone mixed solvent (weight ratio toluene/methyl ethyl ketone = 70/30) to prepare a solid content concentration of 32 Composition II for forming light diffusion layer in weight %. In addition, the aforementioned organoclay system was diluted with toluene to a solid content of 6% by weight and then used.

The composition II for forming the light diffusion layer was coated on the same transparent plastic film substrate as in Example 1 using a wire rod. After heating at 90°C for 1 minute, a high-pressure mercury lamp was used to irradiate ultraviolet rays with a cumulative light amount of 300mJ/cm ² . In the above manner, a light diffusion film having a transparent base layer and a light diffusion layer (thickness 5.7 µm) with an intermediate layer formed therebetween was obtained.

[Comparative Example 2] A light diffusion film was obtained in the same manner as in Comparative Example 1, except that the light diffusion layer was formed to have a thickness of 5.9 μm.

[Comparative Example 3] A light diffusion film was obtained in the same manner as in Comparative Example 1, except that the light diffusion layer was formed to have a thickness of 6.2 μm.

[Comparative Example 4] A light diffusion film was obtained in the same manner as in Comparative Example 1, except that the light diffusion layer was formed to have a thickness of 6.3 μm.

[Comparative Example 5] A light diffusion film was obtained in the same manner as in Comparative Example 1, except that the light diffusion layer was formed to have a thickness of 6.5 μm.

[Comparative Example 6] Mix 50 parts by weight of neopentylerythritol triacrylate (PETA; manufactured by Osaka Organic Chemical Co., Ltd., trade name "Viscoat #300") as a binder resin and urethane acrylate prepolymer (manufactured by Shinnakamura Chemical Industry Co., Ltd.) , Trade name "UA-53H-80BK") 50 parts by weight, polysiloxane particles (manufactured by Momentive Performance Materials Co., Ltd., trade name "Tospearl 130", weight average particle size: 3µm, |D90-D50|: 2.5µm, refractive index: 1.42) 3.5 parts by weight, organic clay synthetic bentonite (manufactured by Co-op Chemical Co., Ltd., trade name "LOOSENTIGHT SAN") 2 parts by weight, photopolymerization initiator (manufactured by BASF) , Brand name "IRGACURE 907") 3 parts by weight and leveling agent (manufactured by DIC Corporation, brand name "PC4100", solid content 10%) 0.2 parts by weight, and toluene/cyclopentanone (CPN) mixed solvent (weight ratio Toluene/cyclopentanone=70/30) was diluted to prepare a composition III for forming a light diffusion layer with a solid content concentration of 33% by weight. In addition, the organoclay system was diluted with toluene to a solid content of 6 wt% and then used.

Next, using a comma coater (registered trademark), the composition III for forming a light diffusion layer was applied to a triacetate cellulose (TAC) film (manufactured by Konica Minolta Opto Co., Ltd., trade name "KC4UA", thickness ：40µm), after heating at 80°C for 1 minute, irradiate ultraviolet light with a cumulative light quantity of 300mJ/cm ² with a high-pressure mercury lamp. In the above manner, a light diffusion film including a transparent base layer and a light diffusion layer (thickness: 6.3 μm) and an intermediate layer formed between the transparent base layer and the light diffusion layer was obtained.

The properties of the light-diffusing films of the examples and comparative examples prepared in the above manner were measured in the following manner.

[Concavo-convex shape on the surface of the light diffusion layer (Sm, Rsk, Rz)] According to JIS B0601 (1994 edition), measure the average distance between unevenness Sm (mm), skewness Rsk and ten-point average surface roughness Rz (µm). Specifically, first, a glass plate (manufactured by MATSUNAMI, MICRO SLIDE GLASS, model S, thickness 1.3mm, 45×50mm) was attached to one of the transparent substrates of the light diffusion film of the foregoing examples or comparative examples with an adhesive. The surface on the side opposite to the light diffusion layer was used to produce samples. Next, use a stylus-type surface roughness measuring device (made by Kosaka Laboratories Co., Ltd., high-precision fine shape measuring device, trade name "SURFCORDER ET4000") with a measuring needle with a radius of curvature of R=2µm at the tip (diamond) , Under the conditions of scanning speed 1mm/sec, cutoff value 0.8mm, and measuring length 12mm, measure the surface shape of the light diffusion layer of the aforementioned sample along a fixed direction, and calculate the average distance between concavities and convexities Sm (mm), ten-point average surface roughness Rz (µm) and skewness Rsk. In addition, the aforementioned high-precision fine shape measuring device can automatically calculate the aforementioned measurement values.

[Visual transmittance loss rate] Using a spectrophotometer (trade name U-4100) manufactured by Hitachi High-Tech Co., Ltd., the transmittance spectrum of the light diffusion film of each of the foregoing examples or comparative examples was measured in the wavelength range of 380 nm to 780 nm, and the visual transmittance loss rate was determined. Y is automatically calculated. In addition, only for the transparent plastic film substrate (without the light diffusion layer and the intermediate layer), the transmittance spectrum was measured in the same manner, and the visual transmittance loss rate Y was automatically calculated. Let the visual transmittance loss rate Y of only the transparent plastic film substrate be Y1, and set the visual transmittance loss rate Y of the light diffusion film of the foregoing examples or comparative examples to Y2, and calculate the visual transmittance according to the following mathematical formula Sense of transmittance loss rate. Visual transmittance loss rate (%)=(Y1-Y2)/Y1×100

[Overall Haze] Measure the haze according to JIS K 7136 (2000 edition) using a haze meter (manufactured by Murakami Color Research Institute, trade name "HM-150").

The characteristics of the light-diffusing films of the foregoing Examples and Comparative Examples measured as above are shown in Table 1 below. In addition, in the following Table 1, the unit of the distance Sm between the average unevenness is mm, the skewness Rsk has no unit, the unit of the ten-point average surface roughness Rz is μm, and the unit of the overall haze is %.

[Table 1]

As shown in Table 1, the light diffusion films of Examples 1-10 satisfy both of 0.110≦Sm and Rsk≦0.200. In contrast, the light diffusion films of Comparative Examples 1 to 5 did not satisfy 0.110≦Sm. Regarding the light diffusion films of Comparative Examples 1 to 4, Rsk≦0.200 was not satisfied. In addition, although the light diffusion film of Comparative Example 6 satisfies 0.110≦Sm, it does not satisfy Rsk≦0.200.

The light-diffusion films of Examples 1 to 10 all had a visual transmittance loss rate of 3.0% or less, and it was confirmed that the light transmittance was high. In addition, since the light-diffusing films of Examples 1 to 10 have an appropriate size (height) of the overall haze value, it was confirmed that they have light diffusivity suitable for practical use.

In contrast, the light-diffusion films of Comparative Examples 1 to 6 have a visual transmittance loss rate greater than 3.0%, and light transmittance is low.

Industrial availability As described above, according to the present invention, it is possible to provide a light diffusing film, a method of manufacturing a light diffusing film, an optical member, a display panel for an image display device, and an image display device that can achieve both light diffusibility and light transmittance. The application of the present invention is not particularly limited, and can be used in a wide range of applications, for example, can be applied to any image display device.

This application claims the priority based on Japanese Application Special Application 2019-071238 filed on April 3, 2019, and incorporates all the disclosures here.

10: Light diffusion film 11: Transparent substrate (A) 12: Light diffusion layer (B) 12a: Resin layer 12b: particles 12c: Thixotropy imparting agent

Fig. 1 is a cross-sectional view showing an example of the structure of the light diffusion film of the present invention.

10: Light diffusion film

11: Transparent substrate (A)

12: Light diffusion layer (B)

12a: Resin layer

12b: particles

12c: Thixotropy imparting agent

Claims (19)

A light-diffusion film, which is laminated with a light-diffusion layer on at least one side of a transparent substrate, and is characterized by: Concavities and convexities are formed on the outermost surface of the light diffusion layer side of the light diffusion film, and The aforementioned concave-convex shape satisfies the following mathematical formulas (1) and (2): 0.110≦Sm　　　　　　　　　　　　　　(1) Rsk≦0.200　　　　　　　　　　　　　　(2) In the foregoing mathematical formula (1), Sm is the average distance between the bumps (mm) of the foregoing bumps measured in accordance with JIS B0601 (1994 edition), In the aforementioned formula (2), Rsk is the skewness of the aforementioned uneven shape measured in accordance with JIS B0601 (1994 edition). Such as the light diffusion film of claim 1, its visual transmittance loss rate under the wavelength of 380~780nm is below 3.0%. The light diffusion film of claim 1 or 2, wherein another layer is laminated on the surface of the light diffusion layer opposite to the transparent substrate. A light-diffusion film, which is laminated with a light-diffusion layer and other layers on at least one side of a transparent substrate, and is characterized by: Concave and convex formed on the outermost surface of the aforementioned other layers, and The aforementioned concave-convex shape satisfies the following mathematical formulas (1) and (2): 0.110≦Sm　　　　　　　　　　　　　　(1) Rsk≦0.200　　　　　　　　　　　　　　(2) In the foregoing mathematical formula (1), Sm is the average distance between the bumps (mm) of the foregoing bumps measured in accordance with JIS B0601 (1994 edition), In the aforementioned formula (2), Rsk is the skewness of the aforementioned uneven shape measured in accordance with JIS B0601 (1994 edition). The light diffusion film according to any one of claims 1 to 4, wherein the aforementioned transparent substrate comprises acrylic resin. The light diffusion film according to any one of claims 1 to 5, wherein the transparent substrate is an acrylic film. The light diffusion film according to any one of claims 1 to 6, wherein the light diffusion layer includes a binder resin and a filler. The light diffusion film of claim 7, wherein the aforementioned filler-based particles. The light diffusion film of claim 8, wherein the difference in refractive index between the particles and the binder resin is 0.200 or less. The light diffusion film according to any one of claims 1 to 9, wherein there is an intermediate layer between the transparent substrate and the light diffusion layer, the intermediate layer comprising a resin derived from the transparent substrate and a resin derived from the light diffusion Layer of resin. Such as the light diffusion film of any one of claims 1 to 10, which is used on the back side of the display panel for image display devices. A method of manufacturing a light-diffusing film is a method of manufacturing the light-diffusing film of any one of claims 1 to 11, the manufacturing method is characterized by comprising the following steps: The light diffusion layer forming step is to form the light diffusion layer on the transparent substrate; and The unevenness forming step is to form the unevenness on the outermost surface of the light diffusion layer side of the light diffusion film in a manner that satisfies the foregoing mathematical formulas (1) and (2); The light diffusion layer forming step includes: a coating step of applying a coating liquid on the transparent substrate; and a coating film forming step of drying the applied coating liquid to form a coating film; and The aforementioned coating liquid contains resin and solvent. The manufacturing method of claim 12, wherein the light diffusion layer forming step further includes a curing step of curing the coating film. The manufacturing method of claim 12 or 13, wherein the aforementioned solvent includes toluene and cyclopentanone. The manufacturing method of any one of claims 12 to 14, wherein the aforementioned light diffusion film is the light diffusion film of claim 3 or 4; and The uneven forming step includes another layer forming step of forming the other layer on the light diffusion layer. An optical member comprising the light diffusion film according to any one of claims 1 to 11. A display panel for an image display device includes the light diffusion film as claimed in claim 11. An image display device comprising the light diffusion film of any one of claims 1 to 11, the optical member of claim 16, or the display panel for an image display device of claim 17. Such as the image display device of claim 18, which includes the display panel for the image display device of claim 17 and the backlight for the image display device.

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